For diabetics, the evaluation of the treatment or control effect of blood glucose includes using hemoglobin A1c (HbA1c) as the best detection target, and an enzyme method is used as the routine clinical detection method. The detection principle of the enzyme method is based on the glycolysis of fructosyl amino acid oxidase (FAOD), in which FAOD is used as the main reaction enzyme, and fructosyl valine (F-V) and fructosyl valyl histidine (F-VH) are used as the reaction substrates to perform the detection of glycated hemoglobin.
Therefore, during glycated hemoglobin detection using an enzyme method, substrate specificity of the fructosyl amino acid oxidase mainly acting as the main reaction enzyme is an essential factor. However, during the hydrolysis of glycated hemoglobin by protease, in addition to the production of F-V and F-VH, a large quantity of fructosyl lysine (F-K) is also relatively produced, and the current FAOD on the market still has a certain affinity for F-K, such that the detection of glycated hemoglobin is affected.
Moreover, the thermal stability of fructosyl amino acid oxidase in the detection kit for detecting glycated hemoglobin on the current market, is less than ideal, and a large amount of stabilizer is often added to the detection kit to improve the stability. However, diagnostic reagents require a certain period of time for storage, such that the requirement for stability is higher. In addition, the stabilizer added thereof often leads to an increase in reagent viscosity, thus affecting subsequent detection.
Therefore, a fructosyl amino acid oxidase with high substrate specificity and thermal stability is urgently needed to accurately quantify glycated hemoglobin and achieve long-term stable preservation.